1. Field of the Invention
The present invention relates to a liquid ejection device and a maintenance method thereof, and more particularly, to a technique for maintaining a line ink-jet head including a plurality of head units connected to each other.
2. Description of the Related Art
Some ink-jet recording devices which form a color image on a recording medium include a line ink-jet head (line head) in which nozzles are provided over a length corresponding to the overall width of the recording medium.
There is a line head in which a plurality of heads (head modules or head units) are connected to each other. The line head has advantages in that it is expected to improve manufacturing accuracy or manufacturing yield and each head can be replaced when a defect is detected in the manufacturing test or when it needs to be replaced due to the occurrence of a failure or the end of the life span.
In the line head including a plurality of heads connected to each other, a gap is provided in a connection portion for connecting the heads in order to absorb the manufacturing error of each head or a positioning error in assembly.
There are problems that mist which is generated during ink ejection or a liquid, such as a cleaning liquid used to wipe a nozzle surface, is likely to accumulate in the gap between the heads and the liquid falls to the recording medium.
In addition, there is a concern that the liquid which accumulates in the gap will flow to the liquid ejection surface when the liquid ejection surface (nozzle surface) is wiped to contaminate the liquid ejection surface or deteriorate the function of the adhesive on the side surface of the head.
JP2006-321172A discloses an ink-jet recording device in which an ink mist stuck to a nozzle surface flows into the gap between ink-jet recording heads 16A subjected to a hydrophilic process, moves up in the gap, and is absorbed by an upper ink absorption member.
JP2002-240308A discloses a structure in which, when a wiper member for removing a foreign material, such as ink stuck to a nozzle plate, is cleaned, the wiper member is moved to a suction hole with negative pressure and the foreign material is removed by suction.
However, in the structure disclosed in JP2006-321172A, when the side surface of the head is lyophilic, ink is likely to accumulate between the side surfaces (the gap between the heads) of the heads and it is difficult to remove the ink using the absorption of the absorption member.
In a case in which the side surface of the head is liquid-repellent, the contact angle of a liquid with low surface tension, such as ink, is equal to or less than 90° even in a liquid-repellent surface and the ink spreads. It is difficult to completely remove the spread ink using the absorption of the absorption member.
There is a concern that the ink remaining on the side surface of the head will drop from the gap and contaminate the recording medium. Even when the ink does not drop from the gap, for example, the adhesive exposed from the side surface of the head deteriorates, which causes the failure of the head.